Gaseous electric discharge device



Feb. 1-1, 1936. KLWIEGAND 2,030,806

GASE OUS ELECTRIC DISCHARGE DEVICE Filed March 25, 1935 Q cjwaa a M BYATTORNEY Patented Feb. 11, 1936 PATENT OFFICE Gaseous anaemic mscnlmenDEVICE Kurt Wiegand, Berlin-Neu-Tempelhoi, Germany, assignor to GeneralElectric Company, a corporation of New York Application March 25, 1935,Serial No. 12,921

In Germany March 29, 1934 4 Claims. (or. 176-122) The present inventionrelates to gaseous electric discharge devices generally andmoreparticularly the invention relates to such devices useful as lightsources. 0 w

The efficiency of gaseous electric discharge lamps having a tubularcontainer filled with'rare gas and operating on high voltage and lowcurrent, that is, a glow discharge lamp, is increased by mountinganother tube closedatboth ends axially in the container and between theelectrodes. The inner tube reduces the discharge space in the containerandincreases, the luminous surface of the discharge with relation to thevolume thereof which increases the efficiency of the lamp.Discharge'lamps of the high'voltage, low current type while useful insigns or the like due to the high surface brilliancy thereof are notuseful as illuminants because such lamps do not emit sufficient light tobepractical for this purpose. Lamps operating on lowvoltage and highcurrent, that is, are lamps, are very useful as light sources. Mountinga tube in the container of the lamp, as above, to increase .theefliciency thereof is not practical in this type of lamp since thedischarge does not distribute itself uniformly in the annular dischargespacein such lamps and the lamp emits an irregular, flickering lightuseless for illuminating purposes.

The object of the present invention is to provide an efficient gaseouselectric discharge lamp of the low voltage, high current type. Stillfurther objects and advantages attaching to the device and to its useand operation will be apparent to those skilled in the art from thefollowing par- 35 ticular description.

I have discovered that the light emitted by tubular, gaseous electricdischarge lamps of the low voltage, high current type, that is, an arclamp, having a closed tube axially mounted in the con- 40 tainer andbetween the electrodes thereof is a steady, non-flickering light whenthe gaseous atmosphere therein consists of or comprises the vapor of avaporizable metal, for example, mercury, or a diflicultly vaporizablemetal, by which I mean a metal the vapor pressure of which at a.temperature of 200 C. is less than 1 mm., such as sodium, cadmium, zinc,or magnesium. My explanation of this phenomenon is that low pressure ofthe metal vapor in the lamp during the operation thereof causes auniform distribution of the arc discharge in the annular discharge spacebetween the electrodes and the light emitted by said discharge is asteady, non-flickering light useful for illumination.

In the drawing accompanying and forming part electrode chambers.

ofthis specification an embodiment of the invention is shown in a frontelevational, partly sectional view.

Referring to the drawing the new and novel gaseous electric dischargedevicecomprises an 5 elongated, tubular, glass container I having athermionic electrode 6 mounted on a current lead 5 sealed therein ateach end thereof and a gaseous atmosphere therein comprising a starting,rare gas, such as neon, argon, or krypton, and a quan- 1o tity ofvaporizable material 2, such as sodium.

'3 to a minimum. A constricted part I I is provided in the walls of saidcontainer I contiguous to said electrodechambers 3. A sealed glass tube1 closed 25 at both ends and having the, longitudinal axis thereofcoincident with the longitudinal axis of said container I is mounted insaid container I withthe ends thereof terminating adjacent said Saidtube I tapers down 30 evenly. from the middle thereof toward both ends.Said tube "I is supported in the longitudinal axis of said container Iby resilient spring members 8 attached thereto and pressing against theinner wall of said container I. A coiled high resistance wire! extendsalong the longitudinal axis of said tube '1 and the ends III of saidwire 9 protrude fromthe ends of said tube 1 toward the adjacentelectrode 6. The center of said wire 9 is supported by the wire I3looped therearound and 40 pressing against the tube I. Said wire 9facilitates the starting of the main discharge between said electrodes6. When desired, the tube] is evacuated or filled with an indifferentgas, such as argon. 4,5

The electric discharge between said electrodes 6 starts in the gas andthe heat of the gas dis' charge raises thetemperature of the-sodium 2 tothe vaporization temperature thereof. During the operation of the lampthe light emitted thereby is rich in rays characteristic of the sodiumvapor and the lamp is a highly efllcient source of light useful forpurposes of illumination. The lamp is a low voltage, high current, arelamp. The electron emitting electrodes 6 make possible 5 to a minimum.

During the operation of the above described lamp the mid-portion of thecontainer I is at as high, if not a higher, temperature as the otherparts thereof due to the fact that the discharge between said electrodes6 is constricted at this part and condensation of the metal vapor cannottake place at said mid-portion. This avoids light obstructing depositsof condensed vapor on said mid-portion. The electrode chambers are at atemperature above the condensation temperature of the metal during'theoperation of the device due to the heating thereof by the electrodes 6,and to the reduction of heat losses therefrom by the insulating material4. The constriction ll likewise prevents deposits of condensed vapor insaid chambers 3. The coolest part of said container I is the regionthereof contiguous to the constriction II and between said constrictionH and the center of container l, but during the operation of the deviceeven this region is above the condensation temperature of the metalvapor.

While I have shown and described and have pointed out in the annexedclaims certain novel features of the invention, it will be understoodthat various omissions, substitutions and changes in the forms'anddetails of the device illustrated and in its use and operation may bemade by those skilled in the art without departing from the broad spiritand scope of the invention, for example, indirectly heated thermionicelectrodes, such as the Hull electrode, are used in place of thedirectly heated electrodes 6, when desired, or, when desired, cold,solid electrodes are used,the tapered tube 1 is not hermetically sealedin the case of a low vapor pressure in the tube, when desired, since thevapor particles do not penetrate into small openings at low pressures; ahigh resistance heater wire connected across the electrodes G is mountedin said tube 1 to heat the vapor in the discharge path, and increase theefliciency of the device, when desired.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:-

1. A gaseous arc discharge lamp comprising a tubularcontainer,'electrodes sealed therein, a' gaseous atmosphere thereincomprising a metal the use of high current densities in the lamp andvapor and a closed tube in said container, a "high electrical resistanceconductor in said tube the ends of said conductor protruding from saidtube and being adjacent said electrodes to facilitate the starting ofthe discharge therebetween', the longitudinal axis of said tube being inthe longitudinal axis of said container and the outside diameter of saidtube being less than the inside diameter of said container to permit thepassage of the arc discharge between said electrodes.

2. A gaseous arc discharge lamp comprising a tubular container,electrodes sealed therein, a

gaseous, atmosphere therein comprising a metal vapor and a closed tubein said container, the longitudinalaxisof said tube being in thelongitudinal axis of said container and the largest outside diameter ofsaid tube being less than the inside diameter of said container topermit the passage of the arc discharge between said elecin saidcontainer, the longitudinal axis of said tube being: in the longitudinalaxis of said container and the largest outside diameter of said tubebeingless than the inside diameter of said container to permit thepassage of the are discharge between said clectrodes, the mid-portion ofsaid tube being the part of largest outside diameter thereof, theoutside diameter of said tube decreasing as'the distance from the centerthereof increases, the ends of said tube being adjacent said electrodes.

4. A gaseous arc discharge lamp comprising a tubular container,electrodes sealed therein, a gaseous atmosphere thereincomprising asodium metal vapor and a closed tube in said container, the longitudinalaxis of said tube being in the longitudinal axis of said container andthe largest outside diameter of said tube being less than the insidediameter of said container to permit the passage of the arc dischargebetween said electrodes, the mid-portionof said tube being the part oflargest outside diameter thereof, the out- 1 side diameter of said tubedecreasing as the distance from the center thereof increases, the endsof said tube being adjacent said electrodes.

KURT WIEGAND.

